Distribution systems of the type having automatic diverter stations for selectively transferring items into diverter pockets from a main transport are well known and in general use both for document and article distribution. Conventional distribution systems include a main transport with a plurality of diverter pockets selectively controlled in accordance with the output of a central controller. Heretofore, it was necessary to provide some form of central controller which was responsive to the progressive locations of articles along the main transport. Diverter pockets are actuated at the proper time in accordance with article progression as determined by distributed sensors. These sensors often take the form of a code reader or photocell position detectors, all providing inputs to the central controller. Thus, the actuation of a diverter pocket from the central controller relied strictly on data derived from items moving in the distribution system.
There are many applications for automated processes requiring the transportation of items (articles and/or documents) from one location to another. Where the distribution of items is required, as in accordance with the system of the present invention, the items are subdivided into multiple groupings in accordance with some particular criterion (or group of criteria) associated with the items. Systems performing such a process incorporate a means for acquiring and characterizing the item and a mechanism for transporting that item to its proper destination, all in accordance with the output of a central controller.
The requirements of the central controller are the subject of the present invention which relates to a method of "tracking" an item through an image of a distribution system. In conventional systems which sort through a large number of destinations, the transportation time associated with an item exceeds considerably the time required to acquire and characterize additional items. This is ineffective in terms of maximal throughput in that it requires the system to handle one item at a time. That is, the item is constantly monitored as it moves through the distribution system. In accordance with the present invention, the system acquires and characterizes an item, then releases the item to the central controller and the proper sortation of the item is considered accomplished without reference to the amount of time subsequently required to finally achieve that result.
Historically, tracking of an item through a distribution system has been accomplished by the use of electronic hardware coupled to the physical transport via sensors, code readers and actuator mechanisms. Generally, there is a sensor/actuator pair associated with each point of possible action in the transport. Thus, the concept underlying these previous tracking techniques has been one of directly monitoring the transport (and the items therein) with the data gathered, then evaluating the data to determine the appropriate response to the conditions implied by the monitoring devices. The implementation of hardware design systems requires coordination of the physical design with the design of the associated electronic hardware of the central controller. This necessitates individualizing the central controller to a specific transport and must be adapted at substantial cost if a different transport design is to be accomodated.